Introduction
Epicardial pacemakers are known as an alternative for endocardial
pacemakers not only for newborns with bradycardia due to sinus node
disease or heart block but also in pediatrics and adults with complex
congenital heart diseases. Regarding newborns and children, rapid
somatic growth, small vessel size, and lack of access to the chamber
requiring pacing make it hard to implement endocardial pacemakers;
therefore, in these cases, permanent epicardial pacemakers are the first
priority. Moreover, congenital heart disease with right-to-left shunts
and intention to preserve venous access and prevent venous thrombosis
(often in pediatric patients) are among other reasons to prefer
epicardial pacemakers.1,2
Endocardial pacemakers showed better longevity than epicardial leads
with higher failure over time mainly due to high thresholds, exit
blocks, and fractures of epicardial leads.3Endocardial pacemakers are implemented in the right side of the heart
and lateral wall of the left ventricle through the coronary sinus, which
is not applicable in 4.3 to 7.5 % of cases due to abnormal venous
anatomy.4,5 Furthermore, studies indicated that
long-term endocardial pacemakers could result in impaired LV
function.6 Otherwise, epicardial leads are directly
applicable on the left ventricle and might be a more appropriate choice
for patients with RV dysfunction.7
Advances in epicardial pacemakers in recent decades resulted in
improvement in the long-term function of these leads. Currently, these
pacemakers have different characteristics, such as being unipolar or
bipolar and steroid-eluting or non-steroid-eluting. Previous studies
demonstrated that steroid-eluting epicardial leads have a comparative
stable pacing threshold.1,8 For instance, a 12-year
follow-up of the children with bipolar steroid-eluting leads illustrated
outstanding sensing characteristics and low median pacing threshold,
making them an appropriate alternative for permanent endocardial
pacemakers.2
Considering the abovementioned indication for epicardial pacemakers,
recent advances, and their various characteristics, it is essential to
evaluate and compare the long-term function of each subtype. In this
study, we aimed to assess the sensing and pacing characteristics, and
survival of different types of epicardial pacemakers and their
associated factors through a 4-year follow-up of all patients who
underwent epicardial pacemaker implantation in the Shaheed Rajaie
Cardiovascular, Medical & Research Center.